docs: write arguments as upper case in manpages

refs #3780, #3864

Change-Id: Iff0534dbd0119734fdb567500fe2e1842c7805f5
diff --git a/docs/manpages/nfd-status-http-server.rst b/docs/manpages/nfd-status-http-server.rst
index a6aa0eb..e4e39eb 100644
--- a/docs/manpages/nfd-status-http-server.rst
+++ b/docs/manpages/nfd-status-http-server.rst
@@ -6,7 +6,7 @@
 
 ::
 
-    nfd-status-http-server [-h] [-p port number] [-a IP address] [-r] [-v]
+    nfd-status-http-server [-h] [-p <PORT>] [-a <IPADDR>] [-r] [-v]
 
 Description
 -----------
@@ -19,10 +19,10 @@
 ``-h``
   Show this help message and exit.
 
-``-p``
+``-p <PORT>``
   HTTP server port number (default is 8080).
 
-``-a``
+``-a <IPADDR>``
   HTTP server IP address (default is 127.0.0.1).
 
 ``-r``